1. Field of the Invention
The invention relates generally to improved digestion technology, e.g., apparatuses and processes for digesting sample materials. In particular, the invention relates to digesters that provide improved fluid transportation and/or sample holder options.
2. Description of Background Art
Paper manufacturing typically requires digestion of a cellulosic material, e.g., wood chips. For example, a cellulosic digestion process may involve impregnating wood chips with fresh cooking liquor (white liquor) and then placing the impregnated chips in a digesting apparatus where they may be heated to cooking temperature. Once cooked down, the cellulosic material is digested and converted into pulp. To create white paper, the pulp is typically then washed, refined, further delignified, and bleached using any of a number of oxidizing agents, e.g., chlorine-based or other high strength oxidizers.
There is a substantial current need for improved pulping apparatuses adaptable to produce paper pulp and/or intermediate fibrous materials rapidly and in high yields. Such apparatuses may be used to produce pulp from a wide variety of cellulosic materials and may be designed to carry out cellulosic digestion in batch or continuous processes. In a conventional batch cooking sulfite process, for example, a digester is filled with wood chips and charged with fresh cooking liquor. The digester is then sealed, and heated to cooking temperature by direct or indirect heating. Once cooked, a substantial portion of the lignin and carbohydrates may be degraded and/or leached from the pulp. Spent cooking liquor (black liquor) and the pulp are separated after cooking.
The laboratory digester is one of the most widely used instruments in the pulp and paper industry. The digester allows a user to experiment with a wide range of chemical compositions in order to optimize the full-scale cooking process. Laboratory digesters are available in a wide range of volumes and may provide critical insight into the chip cooking process for scale-up and/or optimization efforts.
A number of laboratory digesters are commercially available. For example, M/K Systems, Inc. (Bethesda, Md.) manufactures a high-pressure batch process digester that runs pulp-digesting processes on a laboratory scale in a controlled precise manner. Available in both single and dual vessel models, the digester provides excellent control over the cooking profile as well as homogeneous temperature distribution due to excellent systemic flow control. In addition, the digester is suitable for both alkaline and acid digesting process with various types of wood chips and fiber sources. Furthermore, the digester is designed to operate at high temperatures at an elevated pressure.
Nevertheless, there exist opportunities to provide alternatives and improvements to sample digestion technologies. For example, improvements may be made in the areas of fluid-transportation efficiency, higher pressurization, and space utilization. In addition, improvements may be made to provide a range of sample holding options. Such improvements may be useful to overcome shortcomings associated with prior art cellulose digestion processes. In turn, the improvements may be used to address previously unmet and long-felt need to reduce process bottlenecks and improve process efficiencies.